MCQ
The value of $\cos A - \sin A$ when $A = \frac{{5\pi }}{4},$ is
  • A
    $\sqrt 2 $
  • B
    $\frac{1}{{\sqrt 2 }}$
  • $0$
  • D
    $1$

Answer

Correct option: C.
$0$
c
(c) $\cos A - \sin A = \cos \frac{{5\pi }}{4} - \sin \frac{{5\pi }}{4},\left( \because {A = \frac{{5\pi }}{4}} \right)$ 

$ = - \cos \frac{\pi }{4} + \sin \frac{\pi }{4} = - \frac{1}{{\sqrt 2 }} + \frac{1}{{\sqrt 2 }} = 0$.

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